a. Field of the Invention
The invention relates generally to angiographic catheters for injecting a radiopaque material or contrast medium into arteries and/or the heart, for radiological diagnostic purposes. More specifically, the invention relates to an angiographic catheter having a preselected number of dye injection openings of predetermined size, location and orientation so as to provide improved dynamic stability of the catheter during high-pressure ventricular angiography so as to minimize the potential risk of causing ectopic beats or fibrillation, and also to improve reliability of the angiographic diagnosis.
b. Description of the Prior Art
In coronary angiography, a tip of a catheter is inserted into a brachial, axillary or femoral artery and from there advanced into the portion of the aorta proximal to the coronary ostia.
With certain catheters, after the coronary arteries are located, radiopaque dye is injected for visualization of those arteries. In ventricular angiography, the catheter tip of, for example, a femoral ventricular catheter is advanced further into the heart, and the dye is then injected for radiographic visualization. The dye may be injected at volumetric flow rates of, e.g., ten to twenty milliliters per second for several seconds, and at relatively high pressures on the order of about one thousand pounds per square inch (psi) or more, with a pressure rise time of about 0.5 second, as is customary. Maximum peak fluid pressures may reach or exceed 1,300 psi.
Various shapes and designs have been proposed and used for ventricular angiography. For example, a catheter may be a generally straight catheter with an open end and a plurality of spaced sidewall openings adjacent the open end. In one type of loop catheter commonly described as a having a "pigtail" shape, a loop is formed on the distal end portion of the catheter, extending in a plane including the long axis of the catheter. Holes through the outer wall proximal to the loop and at the end of the catheter produce a dispersed pattern of dye injection.
It is known, however, that movement of the catheter tip during angiography adversely affects the utility of the diagnostic procedure. Furthermore, in some instances the catheter tip movement may be potentially harmful to the patient because the tip may impact the heart or vessel walls potentially causing fibrillation, asystole or arrhythmia, or may even dislodge an arteriosclerotic plaque. Because a significant proportion of patients undergoing diagnostic coronary angiography are found to have no significant coronary artery disease, there is a general need to reduce risks to the patients which arise solely from the diagnostic techniques employed.
In a configuration directed to the problem of catheter tip movement, a non-whip catheter is disclosed in U.S. Pat. No. 4,736,620, issued to Oscar F. Ruiz. The "non-whip" catheter includes a curved end resembling the general shape of a shepherd's staff or hook, wherein the open end of the distal tip faces back in the direction of the catheter and generally parallel to the catheter A first opening in the catheter sidewall opposed and spaced from the distal tip directs an interfering stream of dye at the main stream exiting from the tip for stream breakup and mixing. A second opening in the catheter sidewall on the opposite side of the catheter from the first sidewall opening provides a reaction force so as to prevent movement of the catheter at the moment of dye injection.
While the design of U.S. Pat. No. 4,736,620 represents an improvement over previous catheter designs, it has been found the dye exiting the reaction force opening of the non-whip catheter can stimulate the coronary walls so as to create the potential for random ectopic beats or minor ventricular fibrillation so as to render the angiogram non-diagnostic. In other instances, the strength of the reaction force jet may cause turbulence or other undesirable flow patterns within the blood vessel or the heart so as to reduce the diagnostic value of the angiogram.